Microbiology Glossary
Browse our comprehensive collection of 777 microbiology terms and definitions.
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Abiogenesis
Abiogenesis is the natural process by which life is thought to have arisen from non‑living chemical substances on early Earth. It posits that the earliest life...
Abiotic
Abiotic describes all the non‑living parts of an ecosystem, such as sunlight, air, water and minerals. These factors are not alive but they shape where and how...
ABR (Antibiotic resistance)
Antibiotic resistance ABR is the ability of bacteria and other microorganisms to survive and grow in the presence of an antibiotic that would normally kill...
Acid-Fast Bacteria
Acid-fast bacteria are a group of organisms with cell walls that resist decolorization by acidic alcohol during staining because of a high content of mycolic...
Acid-Fast Stain (Ziehl–Neelsen)
The acid-fast stain, often called the Ziehl–Neelsen stain, is a differential staining technique used to identify bacteria with waxy cell walls that retain...
Acidophile
An acidophile is an organism that grows optimally in acidic environments, typically at pH values below 3. Explanation Acidophiles belong to a broader group of...
Actinomycetes/Actinobacteria
Actinomycetes, also called Actinobacteria, are Gram‑positive bacteria with high G+C content. They grow as branching filaments that resemble fungal hyphae and...
Activator
An activator is a regulatory molecule that increases the activity of a biological process, often by enhancing gene transcription or enzyme catalysis. In gene...
Adaptive Immunity
Adaptive immunity is the branch of the vertebrate immune system that develops highly specific responses to antigens and provides long-lasting protection...
Adeno-Associated Virus 1 (AAV1)
Adeno‑Associated Virus 1 AAV1 is a natural serotype of adeno‑associated virus originally isolated from primate tissues. It is a small non‑enveloped virus with...
Adeno-Associated Virus 2 (AAV2)
Adeno‑Associated Virus 2 AAV2 is a human serotype of adeno‑associated virus discovered in 1965 as a contaminant of adenovirus preparations. It is a...
Adeno-Associated Virus 3 (AAV3)
Adeno‑Associated Virus 3 AAV3 is a human serotype of adeno‑associated virus closely related to AAV2. It is a non‑enveloped virus with an icosahedral capsid and...
Adeno-Associated Virus 4 (AAV4)
Adeno‑Associated Virus 4 AAV4 is a serotype of adeno‑associated virus isolated from rhesus monkeys. Like other AAVs it is non‑enveloped with an icosahedral...
Adeno-Associated Virus 5 (AAV5)
Adeno‑Associated Virus 5 AAV5 is a human serotype of adeno‑associated virus. It has a non‑enveloped icosahedral capsid about 25 nm in diameter and a...
Adeno-Associated Virus 6 (AAV6)
Adeno-associated virus 6 AAV6 is a hybrid serotype of adeno associated virus that shares nearly identical capsid sequences with AAV1 and AAV2. It is a small...
Adeno-Associated Virus 7 (AAV7)
Adeno‑associated virus 7 AAV7 is a parvovirus serotype originally isolated from rhesus macaque tissues. Like other adeno‑associated viruses, it is a small...
Adeno-Associated Virus 8 (AAV8)
Adeno‑associated virus 8 AAV8 is a naturally occurring adeno‑associated virus serotype first isolated from rhesus macaque tissues. It is a small non‑enveloped...
Adeno-Associated Virus 9 (AAV9)
Adeno‑associated virus 9 AAV9 is a naturally occurring serotype first isolated from a human sample in 2004. It is a small non‑enveloped parvovirus with a...
Adenovirus
Adenovirus is a medium‑sized non‑enveloped virus with an icosahedral capsid and a linear double‑stranded DNA genome. It belongs to the family Adenoviridae....
Adhesin
An adhesin is a molecule on the surface of a microorganism that mediates attachment to host cells, tissues or abiotic surfaces. These proteins, lipoproteins or...
Adhesion
Adhesion in microbiology is the ability of a cell or virus to attach to a surface, host tissue or another microorganism. It is often the first step in...
Adjuvant
An adjuvant is a substance that is added to a vaccine or immunizing preparation to enhance the body’s immune response to the antigen. Explanation Early...
Aerobes
Aerobes are microorganisms that require molecular oxygen for growth and survival. They use oxygen as the terminal electron acceptor in the electron transport...
Aerotolerant
Aerotolerant organisms are microorganisms that do not use oxygen for energy production but can survive and grow in its presence. They rely on fermentation or...